"Noise canceling" and "earplugs" don't really go hand-in-hand. Sound vibrations are collected by the entire outer ear, funneled into the canal and inner ear (think: kind of like speaking into a megaphone). Blocking the ear canal dampens most of the inbound sound, but the outer ear will continue to pick up ambient vibrations.
In real world terms, even with really good earplugs/earbuds, a certain amount of ambient sound will still transmit "into your head" via vibration. For me, it's higher pitches that bleed through (think: female voice, kids). For others, it's midrange that gets through.
If you want to avoid full ear coverage (headphones) your best bet is:
1. Find a really, really good set of audio earbuds
2. Listen to a white noise program on your mobile device (I'm partial to White Noise Pro, on my iPhone and iPad)
If you're in hopes of canceling noise to sleep, begin using the app each night at home (with or without earbuds) about two weeks before departure, acclimating yourself to it. Makes a BIG difference.
I use White Noise Pro for both sound canceling and my alarm in hotels. Given how often that is, the custom mix I created has a Pavlovian effect. I hear it...I sleep.
Hope that helps...happy travels!